Ntuple

Gate输出里有一个 /gate/output/root/setRootNtupleFlag 1

ROOT里关于Ntuple的说明：

In case you want to store large quantities of same-class objects, ROOT has designed the TTree and TNtuple classes specifically for that
purpose. The TTree class is optimized to reduce disk space and enhance access speed. A TNtuple is a TTree that is limited to only hold floating-point numbers; a TTree on the other hand can hold all kind of data, such as objects or arrays in addition to all the simple types.